1. Technical Field
This disclosure relates to an image forming apparatus including a carriage on which a recording head is mounted.
2. Description of the Background
Image forming apparatuses are used as printers, facsimile machines, copiers, plotters, and multi-functional devices combining several of the foregoing capabilities. As one such image forming apparatus an inkjet recording apparatus is known that employs a liquid-ejection recording method, in which the apparatus performs image formation (hereinafter, recording, printing, and imaging are used as synonyms thereof) by ejecting ink droplets from a recording head onto a sheet transported from a sheet tray.
Liquid-ejection image forming apparatus may be further classified into serial-type and line-type apparatuses. A serial-type image forming apparatus moves a recording head in a main scan direction while ejecting droplets therefrom to form an image, whereas a line-type image forming apparatus uses a line head to eject droplets without moving the recording head.
A conventional serial-type image forming apparatus includes a carriage scanning mechanism to reciprocally move, or scan, a carriage containing a recording head back and forth in a direction perpendicular to a direction in which a sheet is transported. In the carriage scanning mechanism, the carriage is connected to a timing belt extended between a driving pulley and a driven pulley, and the driving pulley is rotated by a driving motor.
In one example, a conventional printer includes in the carriage a document reading unit to read an image of a document by scanning the document in a width direction perpendicular to a transport direction of the document and a printing unit to print a recording sheet using an inkjet print method by scanning the recording sheet in a width direction perpendicular to a transport direction of the recording sheet. The printing unit has substantially the same weight as the document reading unit, and the document and the recording sheet are transported along a transport path common to the document reading unit and the printing unit. Further, a drive-force-transmitting linear member for transmitting drive force from a common driving source is disposed in such an endless loop form that linear portions at both ends extend in a width direction of the transport path, and the document reading unit and the printing unit are mounted on the respective linear portions located at substantially diagonally opposed positions with respect to the center of the loop of the linear member.
As the weight of the carriage mounting a recording head becomes heavier, the inertial force of the carriage during scanning increases. Therefore, a relatively heavy carriage may cause vibration or shock upon impact to an image forming apparatus as the carriage reaches the end of its scan run.
Conventionally, a balancer or an image reading unit having the same weight as a carriage is employed to suppress such vibration or shock. However, little attempt has been made to reduce the weight of the carriage itself.